Modification in active power-frequency loop of virtual synchronous generator to improve the transient stability

摘要

Virtual synchronous generator (VSG) control scheme has received much attention from researchers as the introduction of rotational inertia to inverters. However, maintaining power-angle stability during the transient state of low inertia microgrids consisting of VSG based distributed generation units is a critical challenge. According to the equal-area criterion, the accelerating and decelerating area play an important role in power system stabilisation. Therefore, a new control strategy based on the equal-area criterion is proposed in this paper. According to the proposed control technique, the auxiliary inertia is incorporated into the governor unit of VSG with an additional power loop. The auxiliary inertia term minimises the difference between the governor unit of VSG and the governor unit of the conventional synchronous generator (SG). In contrast, the additional power loop supplies the auxiliary power during the transient process only when a significant fault occurs. Moreover, to enhance the transient stability, auxiliary inertia helps to improve the convergence time and dynamic characteristics of VSG, and additional power helps to shorten the acceleration area and widen the deceleration area. MATLAB/Simulink based simulations analysis and results validate the effectiveness of proposed control.